Analysis of X-ray scattering and diffraction profile for the uniaxial tensile specimens of polyethylene films at different deformation stages have been performed at room temperature. The results show that within elastic region before yielding and post-yield region, the micros-train (distortion) increases notably and the micrograin size does not change much, but within constant stress region of plastic flow, micrograin size decreases rapidly and microstrain changes only a little.